This invention relates to the filling of flat flexible bags, each of which is formed from plastic film and is provided with a spout, of semi-rigid plastic, through which the bag is both filled and emptied. This type of bag is usually supplied flat with a cap in position on its spout, the cap being applied to the spout by an axial inward push on the cap and being removable by an axial outward pull thereon, facilitated by peripheral flanges or ribs provided on both the cap and the spout.
Automatic filling machines for liquids and semi-liquids are generally provided in the form of in-line and rotary fillers. The rotary fillers are most commonly in use because they are for the most part continuous motion machines which operate more smoothly at a high capacity and have a minimum number of parts. The automatic rotary fillers now commonly in use are generally designed to handle and fill rigid or semi-rigid containers which are handled by conventional means such as augers, star wheels, empty containers pushing filled ones, etc. Also, the rigid or semi-rigid containers are often used as the measuring means in filling and controlling the filling operation. Obviously, the flat flexible bags to be filled according to this invention cannot be handled by such conventional means and cannot be used as the measuring means or control means to filling.
Automatic machines now in use for filling flexible containers are generally designed for filling pouches, which are usually made of plastic film or foil and do not have spouts. Pouches are frequently produced and filled on the same machine, commonly known in the trade as form-fill machines, and pouches made on such machines are usually quite small, starting at a fraction of an ounce and usually include piston-displacement measurement or timed fill. Obviously, such machines would not be suitable for filling the relatively large spouted flexible bags starting at about four liters, with which the present invention is concerned. One prior art machine is designed to fill flexible spouted bags but has a single fixed filler head and is not a continuous rotary filler.